I have the exact same problem. It was about time for a reformat so I did that and after resinstall it still does the same thing... After clicking play it doesn't even launch. Before the Draven patch everything was fine.

Hah, good one. They know us LoL addicts need some form of LoL, so they said, "Hey, let's make the launcher work, so they can read MLG is going on, then not let them play. After a while they will get bored of trying to fix LoL and settle for hearing us bable about the game they should be playing, BRILLIANT."